Vehicle

ABSTRACT

A vehicle includes an electric-device temperature acquisition unit, a charging controller, and a predicted charging time deriving unit. The electric-device temperature acquisition unit acquires a temperature of an electric device disposed in a current path for external charging for supplying electric power from a power supply external to the vehicle to a battery mounted in the vehicle. The charging controller pauses a supply of electric power to the battery in response to the temperature of the electric device becoming greater than or equal to a first threshold during the external charging, and resumes the supply of electric power to the battery in response to the temperature of the electric device becoming less than a second threshold lower than the first threshold. The predicted charging time deriving unit derives a predicted charging time predicted to be taken for the external charging in accordance with an instruction for the external charging.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent ApplicationNo. 2020-066612 filed on Apr. 2, 2020, the entire contents of which arehereby incorporated by reference.

BACKGROUND

The disclosure relates to a vehicle that is externally chargeable.

In a vehicle such as an electric vehicle or a plug-in hybrid electricvehicle, a battery mounted in the vehicle is chargeable (externallychargeable) by a power supply external to the vehicle (for example,Japanese Unexamined Patent Application Publication No. 2013-207927).

SUMMARY

An aspect of the disclosure provides a vehicle including anelectric-device temperature acquisition unit, a charging controller, anda predicted charging time deriving unit. The electric-device temperatureacquisition unit is configured to acquire a temperature of an electricdevice disposed in a current path for external charging for supplyingelectric power from a power supply external to the vehicle to a batterymounted in the vehicle. The charging controller is configured to pause asupply of electric power to the battery in response to the temperatureof the electric device becoming greater than or equal to a firstthreshold during the external charging, and resume the supply ofelectric power to the battery in response to the temperature of theelectric device becoming less than a second threshold lower than thefirst threshold. The predicted charging time deriving unit is configuredto derive a predicted charging time that is a time predicted to be takenfor the external charging in accordance with an instruction for theexternal charging. The predicted charging time is a sum of a totalsupply time and a pause time. The total supply time is a total timeduring which electric power is supplied to the battery. The pause timeis a period of time from when the supply of electric power to thebattery is paused to when the supply of electric power to the battery isresumed.

An aspect of the disclosure provides a vehicle including anelectric-device temperature acquisition unit and a predicted chargingtime deriving unit. The electric-device temperature acquisition unit isconfigured to acquire a temperature of an electric device disposed in acurrent path for external charging for supplying electric power from apower supply external to the vehicle to a battery mounted in thevehicle. The predicted charging time deriving unit is configured toderive a predicted charging time that is a time predicted to be takenfor the external charging in accordance with an instruction for theexternal charging. When an expected temperature of the electric deviceat a time of completion of the external charging is predicted to begreater than or equal to a travel-preparation threshold, the predictedcharging time deriving unit is configured to derive a travel-preparationtime and extends the predicted charging time by the travel-preparationtime. The travel-preparation time is a period of time from the time ofcompletion of the external charging until the temperature of theelectric device becomes less than the travel-preparation threshold.

An aspect of the disclosure provides a vehicle including circuitry. Thecircuitry is configured to acquire a temperature of an electric devicedisposed in a current path for external charging for supplying electricpower from a power supply external to the vehicle to a battery mountedin the vehicle. The circuitry is configured to pause a supply ofelectric power to the battery in response to the temperature of theelectric device becoming greater than or equal to a first thresholdduring the external charging, and resume the supply of electric power tothe battery in response to the temperature of the electric devicebecoming less than a second threshold lower than the first threshold.The circuitry is configured to derive a predicted charging time that isa time predicted to be taken for the external charging in accordancewith an instruction for the external charging. The predicted chargingtime is a sum of a total supply time and a pause time. The total supplytime is a total time during which electric power is supplied to thebattery. The pause time is a period of time from when the supply ofelectric power to the battery is paused to when the supply of electricpower to the battery is resumed.

An aspect of the disclosure provides a vehicle including circuitry. Thecircuitry is configured to acquire a temperature of an electric devicedisposed in a current path for external charging for supplying electricpower from a power supply external to the vehicle to a battery mountedin the vehicle. The circuitry is configured to derive a predictedcharging time that is a time predicted to be taken for the externalcharging in accordance with an instruction for the external charging.When an expected temperature of the electric device at a time ofcompletion of the external charging is predicted to be greater than orequal to a travel-preparation threshold, the circuitry is configured toderive a travel-preparation time and extend the predicted charging timeby the travel-preparation time. The travel-preparation time is a periodof time from the time of completion of the external charging until thetemperature of the electric device becomes less than thetravel-preparation threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this specification. The drawings illustrate an embodiment and,together with the specification, serve to explain the principles of thedisclosure.

FIG. 1 is a schematic diagram illustrating a configuration of a chargingsystem according to an embodiment of the disclosure;

FIGS. 2A and 2B are diagrams illustrating an example of the state ofcharge (SOC) and electric-device temperature of a battery duringexternal charging;

FIGS. 3A and 3B are diagrams illustrating another example of the SOC andelectric-device temperature of the battery during external charging;

FIGS. 4A and 4B are diagrams describing a predicted charging time;

FIGS. 5A and 5B are diagrams describing effects of the derivation of atravel-preparation threshold;

FIG. 6 is a flowchart illustrating a process for the derivation of thepredicted charging time; and

FIG. 7 is a flowchart illustrating a correction process.

DETAILED DESCRIPTION

A vehicle that is externally chargeable includes various electricdevices, such as a relay, in a current path between a charging port anda battery. During external charging, current flows through the electricdevices, and the temperature of the electric devices increases. If thetemperature of the electric devices becomes greater than or equal to apredetermined threshold during external charging, the external chargingmay be temporarily paused to prevent the increase in the temperature ofthe electric devices.

Prior to the start of the external charging, the charging time ispredicted. If the external charging is temporarily paused while theexternal charging is ongoing, a difference may occur between thepredicted charging time and the actual charging time.

It is therefore desirable to provide a vehicle with improved predictionaccuracy of the charging time. In the following, an embodiment of thedisclosure is described in detail with reference to the accompanyingdrawings. Note that the following description is directed to anillustrative example of the disclosure and not to be construed aslimiting to the disclosure. Factors including, without limitation,numerical values, shapes, materials, components, positions of thecomponents, and how the components are coupled to each other areillustrative only and not to be construed as limiting to the disclosure.Further, elements in the following embodiment which are not recited in amost-generic independent claim of the disclosure are optional and may beprovided on an as-needed basis. The drawings are schematic and are notintended to be drawn to scale. Throughout the present specification andthe drawings, elements having substantially the same function andconfiguration are denoted with the same numerals to avoid any redundantdescription.

FIG. 1 is a schematic diagram illustrating a configuration of a chargingsystem 1 according to this embodiment. The charging system 1 includes avehicle 10 and an external charger 12.

Examples of the vehicle 10 include an electric vehicle and a plug-inhybrid electric vehicle. The vehicle 10 includes a battery 20 to supplyelectric power to a motor (not illustrated), which is a drive source.The battery 20 is, for example, a secondary battery such as alithium-ion battery. The vehicle 10 also includes a charging port 22 tobe coupled to the battery 20. The charging port 22 is disposed in, forexample, a side surface of the body of the vehicle 10.

The external charger 12 is coupled to, for example, a power supply 30(external power supply) external to the vehicle 10. Examples of thepower supply 30 include a power generation facility of a power company.The external charger 12 has a charging connector 32 connectable to thecharging port 22 of the vehicle 10. The external charger 12 is capableof converting electric power supplied from the power supply 30 andsupplying the converted electric power to the battery 20 via thecharging connector 32 and the charging port 22. That is, the battery 20mounted in the vehicle 10 is chargeable (externally chargeable) by theexternal charger 12.

The vehicle 10 includes, in addition to the battery 20 and the chargingport 22, a junction box 40, a communication unit 42, an outside airtemperature sensor 44, a notification unit 46, a storage unit 48, and avehicle controller 50.

The junction box 40 is a hollow box. The junction box 40 accommodates acharging circuit 60 and a temperature sensor 62. The charging circuit 60is coupled to the charging port 22 and the battery 20. The chargingcircuit 60 forms a current path between the charging port 22 and thebattery 20. The charging circuit 60 is capable of guiding currentflowing into the charging port 22 to the battery 20. The chargingcircuit 60 is also capable of blocking current flow from the chargingport 22 to the battery 20 by using, for example, a relay, a contactor,or the like.

The charging circuit 60 is constituted by various electric devices 64.That is, the electric devices 64 are disposed in the current path(current path for external charging) between the charging port 22 andthe battery 20. The electric devices 64 include, for example, a relay, acontactor, and a busbar. The electric devices 64 are not limited to theexemplified components and may be components constituting the chargingcircuit 60. The temperature sensor 62 detects the temperature of a spacein the junction box 40.

The communication unit 42 is capable of establishing communication withdevices outside the vehicle 10, for example, the external charger 12.The outside air temperature sensor 44 detects the outside airtemperature around the vehicle 10.

In the vehicle 10, as described in detail below, the charging time forexternal charging is predicted before the external charging is started.The notification unit 46 provides a notification of the predictedcharging time. The notification unit 46 provides a notification of thepredicted charging time by using, for example, a display of a console orthe like. The storage unit 48 is a non-volatile memory such as a harddisk drive. The storage unit 48 stores various kinds of information tobe used by the vehicle controller 50.

The vehicle controller 50 is constituted by a semiconductor integratedcircuit including a central processing unit (CPU), a read-only memory(ROM) storing a program and the like, a random access memory (RAM)serving as a work area, and so on. Although not described in detailherein, the vehicle controller 50 controls the components of the vehicle10, such as a driving mechanism, a braking mechanism, and a steeringmechanism (not illustrated).

Further, the vehicle controller 50 executes a program to also functionas an electric-device temperature acquisition unit 70, a chargingcontroller 72, a predicted charging time deriving unit 74, and atravel-preparation threshold deriving unit 76.

The electric-device temperature acquisition unit 70 acquires thetemperature of the electric devices 64. The temperature of the electricdevices 64 is hereinafter sometimes referred to as the electric-devicetemperature. For example, the storage unit 48 stores in advance aconversion table indicating correlations between the temperature of thespace in the junction box 40 and the electric-device temperature. Theelectric-device temperature acquisition unit 70 acquires the temperatureof the space in the junction box 40 from the temperature sensor 62 andconverts the temperature into the electric-device temperature using theconversion table.

The electric-device temperature acquisition unit 70 may not necessarilyacquire the electric-device temperature using the detection result ofthe temperature sensor 62 described above. For example, theelectric-device temperature acquisition unit 70 may estimate theelectric-device temperature from the voltage applied to the electricdevices 64, the terminal voltage of the battery 20, or the like.

The charging controller 72 controls the external charging of the battery20. For example, the charging controller 72 controls the turning on andoff of the relay, the contactor, or the like, which is an example of theelectric devices 64 in the charging circuit 60, to supply electric powerto the battery 20, stop the supply of electric power, and resume thesupply of electric power.

FIGS. 2A and 2B are diagrams illustrating an example of the state ofcharge (SOC) and electric-device temperature of the battery 20 duringexternal charging. As illustrated in FIG. 2A, the charging controller 72continuously charges the battery 20 for a period from, for example, thepoint in time at which the charging is started (“charge start time”) towhen the SOC of the battery 20 becomes a value indicating a fullycharged battery (“full charge value”). That is, the point in time atwhich the charging is completed (“charge completion time”) is set to thepoint in time at which the SOC reaches the full charge value.

As illustrated in FIG. 2B, a first threshold is set in advance for theelectric-device temperature. The first threshold is set to protect theelectric devices 64. The first threshold is set to be less than or equalto a temperature allowable for the electric devices 64. The chargingcontroller 72 is allowed to supply electric power to the battery 20 fora period from the charge start time to the point in time at which theelectric-device temperature reaches the first threshold (“temperaturereaching time”).

As illustrated in FIGS. 2A and 2B, the charging can be completed for theperiod from the charge start time to the temperature reaching time. InFIG. 2B, a broken line in a period from the charge completion time tothe temperature reaching time indicates an example of theelectric-device temperature that is assumed to increase even after thecharging is completed.

When the charging is completed before the electric-device temperaturereaches the first threshold, the charging controller 72 can continuouslysupply electric power to the battery 20 for a period from the chargestart time to the charge completion time. Hereinafter, the time (totaltime) during which electric power is supplied to the battery 20 duringexternal charging is sometimes referred to as the total supply time.When electric power is supplied in consecutive periods with a pause timedescribed below interposed therebetween, the total supply timerepresents the total time obtained by summing up the time during whichelectric power is supplied before the pause time and the time duringwhich electric power is supplied after the pause time.

The predicted charging time deriving unit 74 derives a predictedcharging time, which is the time predicted to be taken for externalcharging, before the start of external charging. In the exampleillustrated in FIGS. 2A and 2B, electric power is continuously suppliedto the battery 20 until the charge completion time. Thus, the predictedcharging time deriving unit 74 can derive a predicted charging time thatis substantially equal to the actual charging time.

FIGS. 3A and 3B are diagrams illustrating another example of the SOC andelectric-device temperature of the battery 20 during external charging.In the example illustrated in FIGS. 3A and 3B, the electric-devicetemperature reaches the first threshold in a period from the chargestart time to the charge completion time. In FIG. 3A, a broken line in aperiod from the temperature reaching time to the charge completion timeindicates an example of the electric-device temperature obtainedassuming that the charging continues even after the electric-devicetemperature reaches the first threshold.

When the electric-device temperature reaches the first threshold beforethe charging is completed, the charging controller 72 temporarily pausesthe supply of electric power to the battery 20 to prevent theelectric-device temperature from excessively increasing to protect theelectric devices 64.

When the supply of electric power to the battery 20 is paused, theactual charge completion time is delayed with respect to the initialcharge completion time, which is predicted at the charge start time. Asa result, a difference occurs between the predicted charging time, whichis predicted before the charging is started, and the actual chargingtime.

To address this, when predicting the charging time, the predictedcharging time deriving unit 74 also predicts the pause time during whichthe supply of electric power to the battery 20 is temporarily paused,and derives the predicted charging time taking the predicted pause timeinto account. The derivation of the predicted charging time will bedescribed in detail hereinafter.

FIGS. 4A and 4B are diagrams describing the predicted charging time.FIG. 4A illustrates an example change in SOC during external charging.FIG. 4B illustrates an example change in electric-device temperatureduring external charging. The specific changes are not limited to theillustrated ones and may be different depending on the SOC, theelectric-device temperature, the outside air temperature, or the like atthe charge start time.

When the charging is started (ts), the charging controller 72 causes thecharging circuit 60 to supply electric power from the external charger12 to the battery 20. At this time, the battery 20 is supplied withelectric power according to allowed input current. The allowed inputcurrent is current that can be input from the external charger 12 to thebattery 20. Accordingly, as illustrated in FIG. 4A, the SOC of thebattery 20 increases with time after the charge start time (ts).

When the charging is started, current flows through the electric devices64, and the electric devices 64 generate heat in response to currentflow. Since the amount of generated heat is larger than the amount ofheat dissipated by the outside air temperature, as illustrated in FIG.4B, the electric-device temperature increases with time after the chargestart time (ts).

For example, as illustrated in FIG. 4B, the electric-device temperatureis assumed to reach the first threshold at a first time (t1) between thecharge start time (ts) and the charge completion time (tf). When theelectric-device temperature becomes greater than or equal to the firstthreshold, the charging controller 72 temporarily pauses the supply ofelectric power to the battery 20. In one embodiment, the chargingcontroller 72 causes the relay or the like of the charging circuit 60 toturn off to block the current flow into the battery 20.

When the supply of electric power is paused, as illustrated in FIG. 4A,the SOC of the battery 20 does not increase and is maintainedsubstantially at the value obtained at the point in time when the supplyof electric power is paused. Since no current flows, the electricdevices 64 do not generate heat, and heat is dissipated by the outsideair temperature. Thus, as illustrated in FIG. 4B, the electric-devicetemperature gradually decreases from the first threshold.

As illustrated in FIG. 4B, a second threshold is set in advance for theelectric-device temperature. The second threshold is set to a valuesmaller than the first threshold. The second threshold is a criterionfor resuming the charging. It is assumed that the electric-devicetemperature is reduced to a value less than the second threshold at asecond time (t2) between the first time (t1) and the charge completiontime (tf). If the electric-device temperature becomes less than thesecond threshold while the supply of electric power is paused, thecharging controller 72 resumes the supply of electric power to thebattery 20. In one example, the charging controller 72 causes the relayor the like of the charging circuit 60 to turn on to cause current toflow into the battery 20.

When the supply of electric power is resumed, as illustrated in FIG. 4A,the SOC of the battery 20 increases again from the maintained value.Since current flows again, the amount of heat generated by the electricdevices 64 is larger than the amount of dissipated heat. Thus, asillustrated in FIG. 4B, the electric-device temperature increases againfrom the second threshold.

The charging controller 72 repeatedly performs, until the SOC reachesthe full charge value, the operation of pausing the supply of electricpower again when the electric-device temperature reaches the firstthreshold again, and resuming the supply of electric power when theelectric-device temperature falls below the second threshold again whilethe supply of electric power is paused.

In the example illustrated in FIGS. 4A and 4B, the supply of electricpower is paused at a third time (t3), the supply of electric power isresumed at a fourth time (t4), the supply of electric power is paused ata fifth time (t5), and the supply of electric power is resumed at asixth time (t6) before the charge completion time (tf) is reached. Thatis, in the illustrated example, pausing and resuming are each repeatedthree times. The number of times pausing is repeated and the number oftimes resuming is repeated may depend on the SOC, the electric-devicetemperature, the outside air temperature, or the like at the chargestart time.

The period of time from the charge start time (ts) to the first time(t1) at which the electric-device temperature reaches the firstthreshold for the first time after the charging is started is sometimesreferred to as the initial charging time. The period of time from whenthe supply of electric power to the battery 20 is paused to when thesupply of electric power to the battery 20 is resumed (for example, theperiod of time between the first time (t1) and the second time (t2), theperiod of time between the third time (t3) and the fourth time (t4), andthe period of time between the fifth time (t5) and the sixth time (t6))is sometimes referred to as the pause time. The total of all the pausetimes (for example, (t1 to t2)+(t3 to t4)+(t5 to t6)) is sometimesreferred to as the total pause time.

Further, the period of time from when the supply of electric power tothe battery 20 is resumed to when the supply of electric power to thebattery 20 is paused or to when the charging is completed (for example,the period of time between the second time (t2) and the third time (t3),the period of time between the fourth time (t4) and the fifth time (t5),and the period of time between the sixth time (t6) and the chargecompletion time (tf)) is sometimes referred to as the recharging time.The total of all the recharging times (for example, (t2 to t3)+(t4 tot5)+(t6 to tf)) is sometimes referred to as the total recharging time.The total supply time during which electric power is supplied to thebattery 20 (see FIGS. 2A and 2B or FIGS. 3A and 3B) corresponds to thetime obtained by adding the initial charging time and the totalrecharging time together (initial charging time+total recharging time).

The predicted charging time deriving unit 74 derives the sum of theinitial charging time, the total recharging time, and the total pausetime (initial charging time+total recharging time+total pause time) as apredicted charging time. In other words, the predicted charging timederiving unit 74 derives the sum of the total supply time and the totalpause time (total supply time+total pause time) as a predicted chargingtime.

If the supply of electric power is paused before the charging iscompleted, recharging is performed to complete charging. Accordingly,the number of times the supply of electric power is paused (the numberof pauses) and the number of times the supply of electric power isresumed (the number of recharges) are identical. As a result, the numberof recharges may be regarded as the number of pauses.

Since the first threshold and the second threshold are set in advancefor the pause time, the pause time can be derived based on the outsideair temperature. Assuming here that the outside air temperature isconstant during external charging, the amounts of heat dissipated duringthe respective pause times are the same, and the lengths of therespective pause times are equal. As a result, the total pause can bederived by multiplying the number of pauses (the number of recharges) bythe pause time.

The predicted charging time deriving unit 74 derives the total pausetime before the start of external charging, and adds the total pausetime to the total supply time to derive the predicted charging time.Since the total pause time is reflected in the predicted charging time,the predicted charging time can be prevented from deviating from theactual charging time even if external charging is temporarilyinterrupted later while the external charging is ongoing.

In one example, the initial charging time, the pause time, and therecharging time (i.e., the time taken to change the electric-devicetemperature) can be derived using Equation (1) below. In Equation (1),ΔT denotes the temperature difference between before and after thechange in electric-device temperature, I denotes the allowed inputcurrent, R denotes the internal resistance of the electric devices 64, tdenotes the time taken to change the electric-device temperature, Cdenotes the thermal capacity of the electric devices 64, a denotes theheat dissipation coefficient, Tb denotes the current electric-devicetemperature, and To denotes the current outside air temperature. Thefirst term of the right-hand side of Equation (1) represents heatgeneration, and the second term of the right-hand side of Equation (1)represents heat dissipation.

ΔT=(I ² R×t/C)−α(Tb−To)   (1)

The electric devices 64 in the junction box 40 include a componentthrough which current supplied to the motor flows while the vehicle 10travels. This may cause an increase in the electric-device temperatureeven while the vehicle 10 travels.

In addition, some drivers may start driving the vehicle 10 immediatelyafter the completion of external charging. If driving of the vehicle 10is started immediately in a state where the electric-device temperatureat the charge completion time is relatively high, in some cases, theelectric-device temperature may reach the first threshold during thetraveling of the vehicle 10. If the electric-device temperature reachesthe first threshold during the traveling of the vehicle 10, for example,the vehicle controller 50 limits the acceleration or the like of thevehicle 10 to protect the electric devices 64. This may prevent thedriver from driving the vehicle 10 as desired.

Accordingly, when the electric-device temperature at the chargecompletion time is greater than or equal to a travel-preparationthreshold, the charging controller 72 waits for a period from the chargecompletion time to when the electric-device temperature becomes lessthan the travel-preparation threshold although the actual charging iscompleted. The travel-preparation threshold will be described in detailbelow. At the point in time when the electric-device temperature becomesless than the travel-preparation threshold, the charging controller 72issues a notification that the external charging has been completed, andpermits the vehicle 10 to travel.

The charging controller 72 may limit the start of traveling when theelectric-device temperature at the charge completion time is greaterthan or equal to the travel-preparation threshold, and may cancel thelimitation of the start of traveling at the point in time when theelectric-device temperature becomes less than the travel-preparationthreshold.

This may increase the time taken until the electric-device temperaturereaches the first threshold, and prevent the electric-device temperaturefrom reaching the first threshold during the traveling of the vehicle10. As a result, the driver is able to drive the vehicle 10 as desiredeven when the driver drives the vehicle 10 immediately after the vehicle10 is permitted to travel.

In the example illustrated in FIG. 4B, the travel-preparation thresholdis set to a value smaller than the second threshold. In the illustratedexample, the electric-device temperature at the charge completion time(tf) is greater than or equal to the travel-preparation threshold.Hereinafter, the electric-device temperature at the charge completiontime is sometimes referred to as the completion-time temperature. Whenthe external charging is completed, current for the external charging nolonger flows through the electric device 64. Thus, as illustrated inFIG. 4B, the electric-device temperature decreases from thecompletion-time temperature due to heat dissipation by the outside airtemperature.

It is assumed that the electric-device temperature becomes less than thetravel-preparation threshold after the charge completion time (tf).Hereinafter, the point in time at which the electric-device temperaturebecomes less than the travel-preparation threshold after the chargecompletion time is sometimes referred to as the travel permission time(tr). The period of time from the charge completion time to the travelpermission time is sometimes referred to as the travel-preparation time.

When deriving the predicted charging time, the predicted charging timederiving unit 74 predicts an expected electric-device temperature at thecharge completion time (completion-time temperature). For example, thepredicted charging time deriving unit 74 derives the last rechargingtime (for example, t6 to tf) on the basis of the total supply time, theinitial charging time, and the recharging times between the pause times.The predicted charging time deriving unit 74 derives the amount ofincrease in the electric-device temperature during the last rechargingtime on the basis of the last recharging time, the allowed inputcurrent, and the outside air temperature. The predicted charging timederiving unit 74 adds the amount of increase in the electric-devicetemperature during the last recharging time to the second threshold toderive the completion-time temperature.

If the completion-time temperature is predicted to be greater than orequal to the travel-preparation threshold, the predicted charging timederiving unit 74 derives the travel-preparation time. For example, thepredicted charging time deriving unit 74 derives the travel-preparationtime on the basis of the temperature difference between thecompletion-time temperature and the travel-preparation threshold and theoutside air temperature.

The predicted charging time deriving unit 74 adds the predicted chargingtime until the charge completion time and the travel-preparation timetogether to update (correct) the predicted charging time. That is, thepredicted charging time deriving unit 74 extends the predicted chargingtime by the travel-preparation time.

As described above, extending the predicted charging time by thetravel-preparation time prevents the predicted charging time fromdeviating from the time taken until the vehicle 10 is actually permittedto travel even if the vehicle 10 is permitted to travel after theelectric-device temperature becomes less than the travel-preparationthreshold after the completion of charging.

In the case of timer-based charging, the driver or the like typicallysets the charge end time. The predicted charging time deriving unit 74according to this embodiment receives an instruction for timer-basedcharging (instruction to perform timer-based charging). Upon receipt ofthe instruction, the predicted charging time deriving unit 74 derives acorrected predicted charging time.

The charging controller 72 according to this embodiment sets the travelpermission time (tr) to a time before the set charge end time. Thecharging controller 72 sets the time earlier than the travel permissiontime (tr) by the corrected predicted charging time as the charge starttime (ts). At the charge start time (ts), the charging controller 72starts external charging.

As described above, the travel permission time (tr) is set to a timebefore the charge end time in the case of timer-based charging, andexternal charging is started on the basis of the corrected predictedcharging time. This can prevent the electric-device temperature frombecoming greater than or equal to the first threshold even if the driverimmediately drives the vehicle 10 after the charge end time in the caseof timer-based charging.

The larger the load is on the motor for driving the vehicle 10, the morelikely it is that the electric-device temperature increases. Forexample, if a rapid acceleration operation is frequently performedduring the traveling of the vehicle 10, the electric-device temperatureis more likely to increase than when a slow acceleration operation isperformed.

The travel-preparation threshold described above may be, for example, aconstant value set in advance. If the travel-preparation threshold isfixed to a constant value, the electric-device temperature may reach thefirst threshold during the traveling of the vehicle 10 after theexternal charging is completed, depending on the operation of thedriver. In this case, the acceleration or the like of the vehicle 10 maybe limited, and the driver may not be able to drive the vehicle 10 asdesired.

Accordingly, the travel-preparation threshold deriving unit 76 derivesthe travel-preparation threshold on the basis of the amount of increasein the electric-device temperature in the previous travel cycle. Thetravel cycle indicates a period from when the start key of the vehicle10 is turned on to when the start key of the vehicle 10 is turned off.

For example, the electric-device temperature acquisition unit 70sequentially acquires the electric-device temperature during the travelcycle and stores a change in the electric-device temperature in thestorage unit 48. At the end of the travel cycle, the electric-devicetemperature acquisition unit subtracts the minimum value of theelectric-device temperature during the travel cycle from the maximumvalue of the electric-device temperature during the travel cycle toderive an amount of increase in the electric-device temperature duringthe current travel cycle, and stores the amount of increase in thestorage unit 48. The amount of increase in the electric-devicetemperature during the travel cycle increases as, for example, thenumber of times the rapid acceleration operation is performed increases.

The travel-preparation threshold deriving unit 76 reads amounts ofincrease in the electric-device temperature during the most recentseveral travel cycles from the storage unit 48 and derives a typicalvalue of the amounts of increase in the electric-device temperature. Thetypical value of the amounts of increase in the electric-devicetemperature is, for example, but not limited to, the maximum value ofthe read values. Alternatively, the typical value of the amounts ofincrease in the electric-device temperature may be the average value orthe like of the read values.

The travel-preparation threshold deriving unit 76 subtracts the typicalvalue of the amounts of increase in the electric-device temperature fromthe first threshold and sets the resulting value as a travel-preparationthreshold. Accordingly, the travel-preparation threshold is set to alower value as the rapid acceleration operation is performed morefrequently in the most recent several travel cycles.

FIGS. 5A and 5B are diagrams describing effects of the derivation of thetravel-preparation threshold. FIG. 5A illustrates an example change inbattery temperature. FIG. 5B illustrates an example change inelectric-device temperature. FIGS. 5A and 5B exemplarily illustrate acase where the vehicle starts traveling immediately after the travelpermission time (tr). In FIG. 5B, a one-dot chain line A10 indicates anexample in which a slow acceleration operation is performed from aconstant travel-preparation threshold (Th1). A two-dot chain line A12indicates an example in which a rapid acceleration operation isperformed from the constant travel-preparation threshold (Th1). A solidline A14 indicates an example in which a travel-preparation threshold(Th2) that is lower than the constant travel-preparation threshold (Th1)is derived in this embodiment, from which a rapid acceleration operationis performed.

As illustrated in FIG. 5A, the temperature (battery temperature) of thebattery 20 increases as the vehicle 10 travels. The battery 20 can fullyexert its performance until the battery temperature reaches theallowable upper limit.

As indicated by the one-dot chain line A10 in FIG. 5B, when a slowacceleration operation is performed, it takes a relatively long time forthe electric-device temperature to reach the first threshold from theconstant travel-preparation threshold (Th1). Thus, in the exampleindicated by the one-dot chain line A10, the battery temperature mayreach the allowable upper limit before the electric-device temperaturereaches the first threshold. In this case, the performance of thebattery can be fully exerted regardless of the electric-devicetemperature.

When a rapid acceleration operation is performed, however, as indicatedby the two-dot chain line A12 in FIG. 5B, the time taken until theelectric-device temperature reaches the first threshold from theconstant travel-preparation threshold (Th1) is shorter than thatindicated by the one-dot chain line A10. As a result, theelectric-device temperature may reach the first threshold before thebattery temperature reaches the allowable upper limit. In this case,while the electric devices 64 are protected, the acceleration of thevehicle 10 is limited due to the electric-device temperature althoughthe performance of the battery 20 can be fully exerted.

As indicated by the solid line A14 in FIG. 5B, in contrast, setting thetravel-preparation threshold Th2 to a low value makes it possible toincrease the time taken until the electric-device temperature reachesthe first threshold, compared with that as indicated by the two-dotchain line A12, even if a rapid acceleration operation is performed. Asa result, the time taken until the electric-device temperature reachesthe first threshold can be delayed with respect to the time taken untilthe battery temperature reaches the allowable upper limit. Accordingly,even if a rapid acceleration operation is performed, the performance ofthe battery 20 can be fully exerted regardless of the electric-devicetemperature.

Further, the travel-preparation threshold deriving unit 76 sets thetravel-preparation threshold to a higher value as the amounts ofincrease in the electric-device temperature in the most recent severaltravel cycles decrease (as the number of times a slow accelerationoperation is performed increases). This prevents the corrected predictedcharging time from increasing more than necessary.

FIG. 6 is a flowchart illustrating a process for the derivation of thepredicted charging time. The predicted charging time deriving unit 74executes the series of processing operations illustrated in FIG. 6 uponreceipt of an instruction for external charging in response to thecharging connector 32 being coupled to the charging port 22.

First, the predicted charging time deriving unit 74 acquires the currentSOC (S100). Then, the predicted charging time deriving unit 74 acquirescharger information from the external charger 12 via the communicationunit 42 (5110). The acquired charger information includes information onthe allowed input current.

Then, the predicted charging time deriving unit 74 derives the totalsupply time of electric power for external charging on the basis of thecurrent SOC and the allowed input current (S120). Here, the total supplytime that does not take the electric-device temperature into account isderived.

Then, the predicted charging time deriving unit 74 acquires the currentoutside air temperature from the outside air temperature sensor 44(S130). Then, the electric-device temperature acquisition unit 70acquires the current electric-device temperature by referring to thetemperature of the temperature sensor 62 (S140).

Then, the predicted charging time deriving unit 74 derives the initialcharging time, which is taken until the electric-device temperaturereaches the first threshold, on the basis of the allowed input current,the current outside air temperature, and the current electric-devicetemperature (S150). Then, the predicted charging time deriving unit 74determines whether the initial charging time is greater than or equal tothe total supply time (S160).

If the initial charging time is greater than or equal to the totalsupply time (YES in S160), the predicted charging time deriving unit 74determines that no recharging based on the electric-device temperatureis performed, and sets the total supply time as the predicted chargingtime (S170). Then, the predicted charging time deriving unit 74 performsthe processing of step S300.

If the initial charging time is less than the total supply time (NO inS160), the predicted charging time deriving unit 74 determines thatrecharging based on the electric-device temperature is performed. Then,the predicted charging time deriving unit 74 performs processing of stepS200 and the subsequent processing. The predicted charging time derivingunit 74 derives the recharging time, which is taken until theelectric-device temperature reaches the first threshold from the secondthreshold, on the basis of the temperature difference between the firstthreshold and the second threshold, the allowed input current, thecurrent outside air temperature, and the current electric-devicetemperature (S200).

Then, the predicted charging time deriving unit 74 derives the number ofrecharges on the basis of the total supply time, the initial chargingtime, and the recharging time (S210). For example, the predictedcharging time deriving unit 74 subtracts the initial charging time fromthe total supply time and divides the resulting value by the rechargingtime to derive the number of recharges.

Then, the predicted charging time deriving unit 74 derives the pausetime, which is taken until the electric-device temperature decreasesfrom the first threshold to the second threshold, on the basis of thetemperature difference between the first threshold and the secondthreshold, the current outside air temperature, and the currentelectric-device temperature (S220).

Then, the predicted charging time deriving unit 74 determines that thenumber of pauses is equal to the number of recharges, and multiplies thepause time by the number of recharges (the number of pauses) to derivethe total pause time (S230).

Then, the predicted charging time deriving unit 74 adds the total pausetime to the total supply time to derive the predicted charging time(S240). Then, the predicted charging time deriving unit 74 performs theprocessing of step S300. In this way, the predicted charging time thattakes into account the pause time caused by the electric-devicetemperature is derived.

In step S300, the predicted charging time deriving unit 74 performs acorrection process for correcting the predicted charging time (S300).Then, the series of processing operations ends. The correction processwill be described below.

FIG. 7 is a flowchart illustrating the correction process (S300). First,the predicted charging time deriving unit 74 derives the electric-devicetemperature at the charge completion time (completion-time temperature)(S310).

Then, the travel-preparation threshold deriving unit 76 derives thetravel-preparation threshold on the basis of the amount of increase inthe electric-device temperature in the previous travel cycle (S320). Thetravel-preparation threshold is not limited to a value less than thesecond threshold and may be greater than or equal to the secondthreshold.

Then, the predicted charging time deriving unit 74 determines whetherthe completion-time temperature is greater than or equal to thetravel-preparation threshold (S330). If the completion-time temperatureis less than the travel-preparation threshold (NO in S330), thepredicted charging time deriving unit 74 terminates the series ofprocessing operations. In this case, the predicted charging time is notcorrected, and the predicted charging time derived in step S170 or S240of the flowchart illustrated in FIG. 6 is maintained.

If the completion-time temperature is greater than or equal to thetravel-preparation threshold (YES in S330), the predicted charging timederiving unit 74 derives the travel-preparation time on the basis of thetemperature difference between the completion-time temperature and thetravel-preparation threshold, the current outside air temperature, andthe current electric-device temperature (S340).

Then, the predicted charging time deriving unit 74 adds thetravel-preparation time and the predicted charging time derived in stepS170 or 5240 together to update (correct) the predicted charging time(S350). Then, the series of processing operations ends. As a result, thepredicted charging time is extended by the travel-preparation time.

As described above, in the vehicle 10 according to this embodiment,during external charging, the supply of electric power to the battery 20is paused when the electric-device temperature becomes greater than orequal to the first threshold, and the supply of electric power to thebattery 20 is resumed when the electric-device temperature becomes lessthan the second threshold. In the vehicle 10 according to thisembodiment, furthermore, in accordance with an instruction for externalcharging, the total supply time during which electric power is suppliedto the battery 20 and the pause time of external charging are addedtogether to derive the predicted charging time.

Accordingly, the vehicle 10 according to this embodiment can improve theprediction accuracy of the charging time.

In the vehicle 10 according to this embodiment, furthermore, if thecompletion-time temperature is predicted to be greater than or equal tothe travel-preparation threshold, the travel-preparation time, which isa period of time from the charge completion time until theelectric-device temperature becomes less than the travel-preparationthreshold, is derived, and the predicted charging time is extended bythe travel-preparation time.

As a result, even if the vehicle 10 according to this embodiment startstraveling immediately after the travel permission time, the time takenuntil the electric-device temperature reaches the first threshold can bedelayed. Accordingly, the vehicle 10 according to this embodiment canprevent the electric-device temperature from reaching the firstthreshold before the battery temperature reaches the allowable upperlimit. As a result, the vehicle 10 according to this embodiment canprevent the performance of the battery 20 from being limited due to theelectric-device temperature without intention.

In the vehicle 10 according to this embodiment, furthermore, thetravel-preparation threshold is derived on the basis of the amount ofincrease in the electric-device temperature in the previous travelcycle. Accordingly, the vehicle 10 according to this embodiment canprevent the electric-device temperature from reaching the firstthreshold during traveling, regardless of the driver.

While an embodiment of the disclosure has been described with referenceto the accompanying drawings, it is to be understood that the disclosureis not limited to the embodiment. It is apparent that a person skilledin the art can make various changes or modifications within the scope asdefined in the appended claims, and it is anticipated that such changesor modifications also fall within the technical scope of the disclosure.

For example, in the embodiment described above, the supply of electricpower to the battery 20 is paused and resumed in accordance with theelectric-device temperature, and the predicted charging time is extendedby the travel-preparation time when the electric-device temperature atthe time of completion of external charging is predicted to be greaterthan or equal to the travel-preparation threshold. However, thepredicted charging time deriving unit 74 may extend the predictedcharging time by the travel-preparation time, regardless of the state ofexternal charging (paused and resumed), when the electric-devicetemperature at the time of completion of external charging is predictedto be greater than or equal to the travel-preparation threshold.

The vehicle controller 50 illustrated in FIG. 1 can be implemented bycircuitry including at least one semiconductor integrated circuit suchas at least one processor (e.g., a central processing unit (CPU)), atleast one application specific integrated circuit (ASIC), and/or atleast one field programmable gate array (FPGA). At least one processorcan be configured, by reading instructions from at least one machinereadable tangible medium, to perform all or a part of functions of thevehicle controller 50 including the electric-device temperatureacquisition unit 70, the charging controller 72, the predicted chargingtime deriving unit 74, and the travel-preparation threshold derivingunit 76. Such a medium may take many forms, including, but not limitedto, any type of magnetic medium such as a hard disk, any type of opticalmedium such as a CD and a DVD, any type of semiconductor memory (i.e.,semiconductor circuit) such as a volatile memory and a non-volatilememory. The volatile memory may include a DRAM and a SRAM, and thenon-volatile memory may include a ROM and a NVRAM. The ASIC is anintegrated circuit (IC) customized to perform, and the FPGA is anintegrated circuit designed to be configured after manufacturing inorder to perform, all or a part of the functions of the modulesillustrated in FIG. 1.

1. A vehicle comprising: an electric-device temperature acquisition unitconfigured to acquire a temperature of an electric device disposed in acurrent path for external charging for supplying electric power from apower supply external to the vehicle to a battery mounted in thevehicle; a charging controller configured to pause a supply of electricpower to the battery in response to the temperature of the electricdevice becoming greater than or equal to a first threshold during theexternal charging, and resume the supply of electric power to thebattery in response to the temperature of the electric device becomingless than a second threshold lower than the first threshold; and apredicted charging time deriving unit configured to derive a predictedcharging time that is a time predicted to be taken for the externalcharging in accordance with an instruction for the external charging,the predicted charging time being a sum of a total supply time and apause time, the total supply time being a total time during whichelectric power is supplied to the battery, the pause time being a periodof time from when the supply of electric power to the battery is pausedto when the supply of electric power to the battery is resumed.
 2. Thevehicle according to claim 1, wherein when an expected temperature ofthe electric device at a time of completion of the external charging ispredicted to be greater than or equal to a travel-preparation threshold,the predicted charging time deriving unit derives a travel-preparationtime and extends the predicted charging time by the travel-preparationtime, the travel-preparation time being a period of time from the timeof completion of the external charging until the temperature of theelectric device becomes less than the travel-preparation threshold. 3.The vehicle according to claim 2, further comprising atravel-preparation threshold deriving unit configured to derive thetravel-preparation threshold on a basis of an amount of increase in thetemperature of the electric device in a previous travel cycle.
 4. Avehicle comprising: an electric-device temperature acquisition unitconfigured to acquire a temperature of an electric device disposed in acurrent path for external charging for supplying electric power from apower supply external to the vehicle to a battery mounted in thevehicle; and a predicted charging time deriving unit configured toderive a predicted charging time that is a time predicted to be takenfor the external charging in accordance with an instruction for theexternal charging, and when an expected temperature of the electricdevice at a time of completion of the external charging is predicted tobe greater than or equal to a travel-preparation threshold, derive atravel-preparation time and extend the predicted charging time by thetravel-preparation time, the travel-preparation time being a period oftime from the time of completion of the external charging until thetemperature of the electric device becomes less than thetravel-preparation threshold.
 5. A vehicle comprising: circuitryconfigured to acquire a temperature of an electric device disposed in acurrent path for external charging for supplying electric power from apower supply external to the vehicle to a battery mounted in thevehicle, pause a supply of electric power to the battery in response tothe temperature of the electric device becoming greater than or equal toa first threshold during the external charging, resume the supply ofelectric power to the battery in response to the temperature of theelectric device becoming less than a second threshold lower than thefirst threshold, and derive a predicted charging time that is a timepredicted to be taken for the external charging in accordance with aninstruction for the external charging, the predicted charging time beinga sum of a total supply time and a pause time, the total supply timebeing a total time during which electric power is supplied to thebattery, the pause time being a period of time from when the supply ofelectric power to the battery is paused to when the supply of electricpower to the battery is resumed.
 6. A vehicle comprising: circuitryconfigured to acquire a temperature of an electric device disposed in acurrent path for external charging for supplying electric power from apower supply external to the vehicle to a battery mounted in thevehicle, derive a predicted charging time that is a time predicted to betaken for the external charging in accordance with an instruction forthe external charging, and when an expected temperature of the electricdevice at a time of completion of the external charging is predicted tobe greater than or equal to a travel-preparation threshold, derive atravel-preparation time and extend the predicted charging time by thetravel-preparation time, the travel-preparation time being a period oftime from the time of completion of the external charging until thetemperature of the electric device becomes less than thetravel-preparation threshold.